1. Field of the Invention
The invention relates to an apparatus adapted for harvesting trees, in particular for cutting and transporting trees in relatively hilly terrain.
2. Prior Art
There are many tree harvesting machines adapted for use in relatively level terrain in which ground gradients rarely exceed a few percent. Also, there are machines for harvesting widely spaced trees which permit use of a relatively large machine which can be cumbersome to manoeuvre to position tree holding and cutting means, eg. grapples and shears prior to cutting. Such machines are generally limited in their application to widely spaced trees growing on level terrain. Furthermore, the devices described above commonly only cut the tree and the fallen tree is then collected by another machine or cable apparatus. Commonly, the shears of such machines usually require extensive maintenance in order to produce acceptable cuts. Notwithstanding such maintenance it is not uncommon for prior art shears to split a tree for many feet longitudinally form the cut, thus incurring excessive waste of lumber.
Many of the prior art machines known to the inventor would be unsuitable for use in relatively mountainous terrain because such machines could not climb the relatively steep gradients, nor pass between relatively closely spaced trees found in forests in mountains, particularly on the west coast of North America. In such terrain, for environmental and practical reasons, it is preferable to move mobile heavy equipment as little as possible. Thus common harvesters which only cut the trees require an additional piece of apparatus to remove the falled trees. If a separate log retrieving vehicle is used the terrain would be subject to passage of at least two vehicles. Alternatively, cable systems could be used but these are limited in their range of application, and are costly and time consuming to reposition for retrieving logs from different areas of the forest.
Furthermore tree harvesting devices known to the inventor are relatively costly, single-purpose machines which represent a large investment and yet can only be used for one purpose, namely harvesting trees. Thus, because such machines can be made idle for long periods of time due to weather conditions, terrain conditions, etc., a relatively long period of time is required for recovery of investment in such machines.